According to observations of naturalists and beekeepers.
Where are you?
Black willow is found throughout the eastern United States, adjacent parts of Canada, and Mexico. Its range extends west from southern New Brunswick and central Maine to Quebec, southern Ontario, central Michigan, southeastern Minnesota, and eastern North Dakota. It occurs south and west to the Rio Grande just below its confluence with the Pecos River; and east along the Gulf Coast through the Florida Panhandle and southern Georgia. Black willow has been introduced in Utah where it is now common along many stream bottoms.
This plant is present in at least 41 states/provinces in this country.
Black willow flowering begins in February in the southern portion of its range and extends through late June at the northern limits. The catkins usually appear at the time of or immediately preceding leaf emergence. Seeds ripen and fall in April to July.
Acer saccharinum (aka: Silver maple, Soft maple)
Ulmus americana (aka: American elm, White elm, Water elm, Soft elm, Florida elm)
Acer negundo (aka: Boxelder, Western boxelder, Arizona boxelder, California boxelder, Texas boxelder, Interior boxelder, Violet boxelder)
Salix nigra (aka: Black willow, Swamp willow, Southwestern black willow, Gulf black willow, Scythe-leaved willow)
Salix lucida (aka: Shining willow, Greenleaf willow, Tail-leaf willow, Whiplash willow, Pacific willow, Lance-leaf willow, Longleaf willow, Red willow, Western shining willow)
Amelanchier arborea (aka: Common serviceberry, Downy serviceberry, Juneberry, Shadbush, Shadblow, Sugarplum)
Malus domestica (aka: Pyrus pumila, Malus pumila, Apple)
Crataegus douglasii (aka: Black hawthorn, Douglas hawthorn, River hawthorn, Western thornapple)
Acer saccharum (aka: Sugar maple, Rock maple, Hard maple)
Prunus americana (aka: American plum, Goose plum, River plum, Wild plum)
Populus tremuloides (aka: Quaking aspen, Trembling aspen, Aspen, American aspen, Mountain aspen, Golden aspen, Trembling poplar, White poplar, Popple, Alamo Blanco)
Prunus pumila (aka: Sandcherry, Western sandcherry, Eastern sandcherry, Great Lakes sandcherry)
Salix bebbiana (aka: Bebb willow, Beak willow, Beaked willow, Long-beaked willow, Diamond willow, Chaton, Petit Minou, Smooth Bebb willow)
Salix discolor (aka: Pussy willow, American pussy willow, Glaucous willow, Large pussy willow)
Acer rubrum (aka: Red maple, Scarlet maple)
Acer platanoides (aka: Norway maple)
Salix lutea (aka: Yellow willow)